Problem: Simplify the following expression: $k = \dfrac{10zy}{12y^2} + \dfrac{4y^2 + 2y}{12y^2}$ You can assume $x,y,z \neq 0$.
Solution: Since the expressions have the same denominator we simply combine the numerators: $k = \dfrac{10zy + 4y^2 + 2y}{12y^2}$ The numerator and denominator have a common factor of $2y$, so we can simplify $k = \dfrac{5z + 2y + 1}{6y}$